Final answer:
Without the specific number of sandwiches representing the opportunity cost for producing 10 lattes, it is impossible to determine the opportunity cost for 1 latte or the cost of a service call on an espresso machine in terms of lattes.
Step-by-step explanation:
The question regarding the cost of a service call on an espresso machine in terms of the number of lattes it equals is an exercise in understanding opportunity cost and unit rate conversion. Opportunity cost represents the potential benefit an individual misses out on when choosing one alternative over another. In terms of the Charlie's opportunity cost, if the opportunity cost to produce 10 lattes is a certain number of sandwiches, then to find the opportunity cost for producing 1 latte, you would divide the number of sandwiches by 10.
Unfortunately, the question does not provide the specific number of sandwiches that is the opportunity cost for producing 10 lattes. Therefore, without additional data, it is impossible to determine Charlie's opportunity cost for 1 latte or convert this opportunity cost into the cost of a service call on an espresso machine. To answer the original question, you would require either the cost of the service call or the cost to make one latte.